When taking a picture it is necessary to know not only in what direction to aim the camera but also how much of the subject will be included in the picture. For this reason practically every camera has a viewfinder of some kind.
Cameras have been proposed, such as disclosed in prior art U.S. Pat. Nos. 5,086,311, issued February 1992, 4,583,831, issued Apr. 22, 1986, and 3,490,844, issued Jan. 20, 1970, that include means for taking pictures which when printed are intended to have different aspect ratios. Each aspect ratio is selected by the photographer before he or she takes the picture. One currently popular aspect ratio in addition to the normal or full frame one, i.e. 1.5:1, in 35 mm photography is between 2:1 and 3:1. An aspect ratio between 2:1 and 3:1 provides a panoramic or stretch format print as compared to the normal format print having an aspect ratio of 1.5:1.
Since it is necessary for the photographer to know how much of the subject will be included in the picture, the viewfinder in these cameras typically will have some masking device or the like for partially masking the viewfinder field to match the aspect ratio selected by the photographer. For example, prior art U.S. Pat. No. 4,973,997, issued Nov. 27, 1990, discloses a masking blade movable to alternatively position a pair of mask openings having panoramic and telephoto aspect ratios, respectively, over a viewfinder window to vary the viewing field. A problem, however, with this design is that the masking blade must move within an area inside the camera body that is at least four times the area occupied by the viewing window. Thus, the size of the camera body may need to be enlarged to accommodate movement of the masking blade.